1. Field of the Invention
The present invention relates to a light-emitting device using an organic compound. More specifically, the present invention relates to an organic light-emitting device using a metal coordination compound as a light-emitting material so as to allow high luminescence efficiency in a stable manner.
2. Related Background Art
An organic electroluminescence (EL) device has been extensively studied for its practical application as a light-emitting device with a high responsiveness and high luminescence efficiency (see, e.g., “Macromol. Symp.”, 125, pp. 1-48 (1997)).
A copper coordination compound can be produced at a comparatively low cost because of inexpensive raw materials. Thus, exploiting the characteristics of the copper coordination compound would lead to a high-performance organic EL device with low cost.
For instance, organic EL devices using copper complexes have been disclosed in Japanese Patent No. 2940514 B and Y. Ma et al., “High Luminescence Gold (1) and Copper (1) complexes with Triplet Excited State for Use in Light-Emitting Diodes”, Advanced Materials, 1999, 11, No. 10, p. 852. However, these EL devices are extremely poor in luminescence efficiency and described insufficiently in these documents in terms of their efficiency. The characteristics of the cooper coordination compound may be insufficiently brought out. Thus, the cooper coordination compound has insufficient property to be used for a display, illumination, or the like.
Furthermore, in “Chemical Review”, 1999, 99, p. 3625-3647 and the proceedings of “the 15th Photochemistry Panel Discussion of Coordination Compound” (Japan), 2001, p. 91, copper coordination compounds are disclosed. However, these documents describe only photoluminescence emitted in a solution or crystalline particle powder, while no luminescence of an organic EL device under excitation with an electric current is described.